Objective: This study investigated the contribution of driver distraction and inattention within fatal and injury crashes using recent in-depth road crash investigation data. To assist in developing system-based solutions, this study also examined the wider context in which inattention-related crashes occurred and the characteristics of inattentive drivers.

Methods: The sample included in-depth crash data from 186 fatal and injury crashes in South Australia investigated from 2014 to 2018. Crash case notes were reviewed to determine whether there was evidence that attentional failures contributed to the crash. Using an adapted taxonomy of inattention, 5 subtypes of driver inattention were defined: Misprioritized attention, neglected attention, cursory attention, diverted attention (distraction), and unspecified inattention. The characteristics of inattention crashes were also compared with those for non-inattention-related crashes.

Results: Of the 160 crashes for which there was sufficient information to determine whether inattention was a factor, 31.3% showed evidence of driver inattention contributing to the crash. The most common subtypes of inattention were distraction (13.8% of all crashes) and driver misprioritized attention (8.1%). The distraction-related crashes included a variety of different distractions, the majority of which were not technology based (e.g., passenger interaction, searching for/adjusting objects, emotional stress, other road users), with those located in-vehicle the most prevalent. Distraction from mobile phone use was identified in 2.5% of all crashes. The majority of distractions were cognitive (64%) and voluntary (77%) in nature. Inattention crashes were most likely to involve right turn/angle or rear-end crash types and occur at intersections, in metropolitan areas, and in lower speed zones.

Conclusions: The findings established that almost a third of fatal and injury crashes involved driver inattention and distraction and many of these could have been prevented. System-wide solutions that could mitigate or prevent distraction crashes include intervening vehicle safety technologies, infrastructure solutions to promote a forgiving road environment, blocking capabilities within technologies to prevent communications while driving, and interventions communicating the risks associated with inattention. Of significance, this study also demonstrated the importance of in-depth data for understanding the contribution of distraction and inattention errors in crash causation.